I'm not a fondant person, but it looks like it was done in panels as opposed to one solid piece (as it appears in your pic). It looks like it was attached in pieces and then matched up at the seems. I could be wrong.

I think it was done in panels, too. But perfectly cut and aligned panels. Or, at the very least, a band that wraps the square around, and meets right on the corner where the lid is resting, so that side is covered.

I am no expert, but if I was asked for a cake wrapped as a present, I would cover the sides with a single wide fondant band and join it at one corner as perfect as I could. Then I would do a lid with fondant just on top, to simulate a box. Kind of how this one looks here, present on bottom.